I was wondering if someone could help me. I'm not expert in audio diy.

I'm building a powered tower speaker that can play mp3 files directly off of a USB memory stick.

The tower speaker has four 5" drivers and a tweeter. I've attached a picture. I purchased the tower speaker used at a very good price and it sounds awesome (on my Marantz NR1402 receiver... that is). The only specs I can see on the speaker are: 200W and 8ohm.

Can someone recommend an amplifier and a power supply that can provide good, clean sound, for low to moderate listening levels (background music, etc.)?

Like I mentioned, I'm not an expert, so I'm just looking to buy an amplifier board and power supply, install them in the speaker cabinet, hook them up to the mp3 module, and that's it. Preferably, I'd like to stay under $100 USD (or CAD) for the amp and power supply.

My fiancee wanted a white noise machine to fall asleep at night. You can already buy high end machines between $100 and $200 but they have horrible sound quality.

For total cost of $120, I made a machine myself.

Fiancee's criteria were: machine must have no lights and needs to be a single tower.

My system has:
-Tower speaker (got 2 for $30 off of kijiji)
-Helder MKIII amp
-MP3 decoder
-Two switching power supplies
-Two 3-way crossovers
-Five drivers: two bass, two mid-range, and one tweeter facing the backk
-Delay on relay hooked to the amp to eliminate popping sound when turning on the machine
-Two 4700uf capacitors hooked to the MP3 decoder to eliminate popping sound when turning off the machine